Re-enabling VTIs

[Rick Hillegas]

I have logged enhancement request 716 to track the re-enabling of 
customer-defined Virtual Table Interfaces (VTIs). A little history follows:

Cloudscape used to let users include arbitrary customer written 
ResultSets in the FROM lists of queries. This provided a very powerful 
ability to impose a tabular face on external data and to join relational 
data with external data streams. It is hard to overestimate the 
usefulness of this feature. Today, Derby still ships a number of 
diagnostic VTIs. However, customer-written VTIs have been disabled. The 
parser raises an error when it sees a VTI that doesn't live in Derby's 
diagnostic packages.

I would like to develop a plan for addressing the concerns which led to 
the disabling of this feature. I would like to see us put this power 
back in our customer's hands.

I can imagine that the non-standard nature of VTI declaration was an 
issue. Are there other issues? Has anyone given some thought to what a 
more acceptable API would look like?

Thanks,
-Rick